1. Field of the Invention.
This invention relates to apparatus for opening and closing garage doors of the side mount type wherein the motor is mounted at the side of the door and operates through a sprocket and chain to open and close the door. More particularly, this invention relates to devices for releasing the door mechanism from the drive mechanism should the drive become inoperative.
2. Description of the Prior Art
Present garage door openers are normally of either the center drive type wherein the motor and drive apparatus is mounted midway between the sides of the door on the ceiling of the garage, or the side mount type wherein the motor and driving apparatus are mounted at one side of the door and driving is accomplished through a sprocket chain assembly. Such garage door openers sometimes become inoperative because of power failures, motor failures and the like. In such circumstances it is still necessary that the garage door be opened and closed and that provision be made for doing so manually.
In order to accomplish manual opening and closing, it becomes necessary to disconnect the drive motor, reduction gears and the like from the door support mechanism. Otherwise, the mechanical characteristics of the motor and gears offers such resistance that manual opening and closing of the doors becomes extremely difficult, if not impossible.
Typically, known side mount door operators are provided with a clutch mechanism between the drive motor and the drive shaft which can be disengaged by various mechanisms so as to disconnect the motor from the drive shaft and thus allow the door to be manually opened or closed. An example of such device is found in U.S. Pat. No. 4,472,910 issued to Kiyoshi Iha on Sept. 25, 1984.
The clutch mechanisms provided in the prior art patents are complicated, expensive, difficult to operate, and are known to get out of order when needed most. Examples of such clutch mechanisms may be found in U.S. Pat. No. 3,066,729 to Glenn P. Gessell, issued Dec. 4, 1962; U.S. Pat. No. 3,512,302 issued to Bernard J. Sivin et al. on May 19, 1970; and U.S. Pat. No. 4,605,108 issued to Bernard Monot on Aug. 12, 1986.
The above-listed patents are believed to be relevant to the present invention because they were adduced by a prior art search made by an independent searcher, and a copy of each of the above-listed patents is supplied to the Patent and Trademark Office herewith.